Python中import机制

# 导入一个模块
import model_name
# 导入多个模块
import module_name1,module_name2
# 导入模块中的指定的属性、方法（不加括号）、类
from moudule_name import moudule_element [as new_name]

# -*- coding:utf-8 -*-
print("This is module_name.py")

name = 'Hello'

def hello():
    print("Hello")

# -*- coding:utf-8 -*-
import module_name

print("This is module_test01.py")
print(type(module_name))
print(module_name)

运行结果：
E:\PythonImport>python module_test01.py
This is module_name.py
This is module_test01.py
<class 'module'>
<module 'module_name' from 'E:\\PythonImport\\module_name.py'>

# -*- coding:utf-8 -*-
from module_name import name

print(name)

运行结果;
E:\PythonImport>python module_test02.py
This is module_name.py
Hello

# -*- coding:utf-8 -*-

print("This is package_name.__init__.py")

# -*- coding:utf-8 -*-
import package_name

print("This is module_test03.py")

运行结果：
E:\PythonImport>python module_test03.py
This is package_name.__init__.py
This is module_test03.py

# -*- coding:utf-8 -*-

print("Hello World")

# -*- coding:utf-8 -*-
# __init__.py文件导入"package_name"中的"hello"模块
from . import hello
print("This is package_name.__init__.py")

运行结果：
E:\PythonImport>python module_test03.py
Hello World
This is package_name.__init__.py
This is module_test03.py

# -*- coding:utf-8 -*-
import module_name 

def a():
    module_name.hello()
    print("fun a")

def b():
    module_name.hello()
    print("fun b")

a()
b()

运行结果：
E:\PythonImport>python module_test04.py
This is module_name.py
Hello
fun a
Hello
fun b

# -*- coding:utf-8 -*-
from module_name import hello 

def a():
    hello()
    print("fun a")

def b():
    hello()
    print("fun b")

a()
b()

运行结果：
E:\PythonImport>python module_test04.py
This is module_name.py
Hello
fun a
Hello
fun b

>>> dir(__builtins__)
['ArithmeticError', 'AssertionError', 'AttributeError', 'BaseException', 'BlockingIOError', 'BrokenPipeError', 'BufferError', 'BytesWarning', 'ChildProcessError', 'ConnectionAbortedError', 'ConnectionError', 'ConnectionRefusedError', 'ConnectionResetError', 'DeprecationWarning', 'EOFError', 'Ellipsis', 'EnvironmentError', 'Exception', 'False', 'FileExistsError', 'FileNotFoundError', 'FloatingPointError', 'FutureWarning', 'GeneratorExit', 'IOError', 'ImportError', 'ImportWarning', 'IndentationError', 'IndexError', 'InterruptedError', 'IsADirectoryError', 'KeyError', 'KeyboardInterrupt', 'LookupError', 'MemoryError', 'NameError', 'None', 'NotADirectoryError', 'NotImplemented', 'NotImplementedError', 'OSError', 'OverflowError', 'PendingDeprecationWarning', 'PermissionError', 'ProcessLookupError', 'RecursionError', 'ReferenceError', 'ResourceWarning', 'RuntimeError', 'RuntimeWarning', 'StopAsyncIteration', 'StopIteration', 'SyntaxError', 'SyntaxWarning', 'SystemError', 'SystemExit', 'TabError', 'TimeoutError', 'True', 'TypeError', 'UnboundLocalError', 'UnicodeDecodeError', 'UnicodeEncodeError', 'UnicodeError', 'UnicodeTranslateError', 'UnicodeWarning', 'UserWarning', 'ValueError', 'Warning', 'WindowsError', 'ZeroDivisionError', '_', '__build_class__', '__debug__', '__doc__', '__import__', '__loader__','__name__', '__package__', '__spec__', 'abs', 'all', 'any', 'ascii', 'bin', 'bool', 'bytearray', 'bytes', 'callable', 'chr', 'classmethod', 'compile', 'complex', 'copyright', 'credits', 'delattr', 'dict', 'dir', 'divmod', 'enumerate', 'eval', 'exec', 'exit', 'filter', 'float', 'format', 'frozenset', 'getattr', 'globals', 'hasattr', 'hash', 'help', 'hex', 'id', 'input', 'int', 'isinstance', 'issubclass', 'iter', 'len', 'license', 'list', 'locals', 'map', 'max', 'memoryview', 'min', 'next', 'object', 'oct', 'open', 'ord', 'pow', 'print', 'property', 'quit', 'range', 'repr', 'reversed', 'round','set', 'setattr', 'slice', 'sorted', 'staticmethod', 'str', 'sum', 'super', 'tuple', 'type', 'vars', 'zip']